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Showing papers on "Total pressure published in 1977"


Journal ArticleDOI
TL;DR: In this paper, a new plasma etching technique using microwave discharge is presented, which is suitable for etching fine patterns of semiconductor devices, and the etching rate becomes maximum (2.6×10-2 µm/min) when the mixing ratio is 20%.
Abstract: A new plasma etching technique using microwave discharge is presented. Silicon wafers are etched by the discharge in a (CF4+O2) gas mixture. Fine patterns with dimensions of 1 µm are etched up to 1 µm in depth without undercutting at a pressure of 5×10-4 Torr with an Al mask having 0.08 µm thickness. Etching is thought to be carried out by chemical reactions. With this technique, the etching rate becomes maximum (2.6×10-2 µm/min) when the mixing ratio γ is 20%. Symbol γ is the partial pressure of O2 divided by the total pressure. The etched depth is proportional to the etching time. This technique is suitable for etching fine patterns of semiconductor devices.

175 citations


Journal ArticleDOI
TL;DR: In this article, the performance of an annular combustor-dump diffuser is investigated and the effect of the pre-diffuser geometry, the distance between the prediffuser outlet and the head of the flame tube and the division of flow between the two concentric annuli is investigated.
Abstract: In this paper results of an experimental investiga- tion of the performance of an annular combustor-dump diffuser are presented. The geometry comprised a straight -walled pre -diffuser followed by a sudden expan - sion in which the flow divides and passes to the two con - centric annuli surrounding the flame tube. Tests were carried out to investigate the influence of: pre -diffuser geometry, the distance between pre -diffuser outlet and the head of the flame tube and, the division of flow between the two concentric annuli. The system is shown to offer good performance and flow stability over a wide range of operating conditions. The way in which the presence of the flame tube improves the performance and stability of flow in the pre-diffuser is demonstrated. Whereas nearly all of the pressure rise occurs in the pre-diffuser most of the total pressure loss occurs near the head of the flame tube. Minimum total pressure loss and a symmetrical pressure distribution on the head of the flame tube was obtained with a symmetrical velocity profile at pre-diffuser outlet. The results also focus attention on the need to carefully match the geometries of the pre -diffuser, flame tube and surrounding annuli. Nomenclature

65 citations


Journal ArticleDOI
TL;DR: In this article, the absolute rate constants for the reaction of OH radicals with ethylene were determined using flash photolysis-resonance fluorescence technique, over the temperature range 299-425 K at total pressures of 25-663 torr of argon.
Abstract: Absolute rate constants for the reaction of OH radicals with ethylene have been determined, using a flash photolysis–resonance fluorescence technique, over the temperature range 299–425 °K at total pressures of 25–663 torr of argon. The rate constants k2 were observed to be pressure dependent below ∼225 torr total pressure, in agreement with other recent studies. The rate constants were independent of total pressure over the range 225–663 torr of argon, and the Arrhenius expression obtained from data over this pressure range was k2=2.18×10−12 e(770±300)/RT cm3 molecule−1⋅sec−1 with a value at 299 °K of k2= (7.85±0.79) ×10−12 cm3 molecule−1⋅sec−1. This room temperature high pressure rate constant is in good agreement with a recent relative rate determination carried out at atmospheric pressure.

61 citations


Journal ArticleDOI
TL;DR: In this paper, the absolute rate constants for the reactions of OH radicals with C2H2 (k1) and CO (k2) have been determined using a flash photolysis-resonance fluorescence technique.
Abstract: Absolute rate constants for the reactions of OH radicals with C2H2 (k1) and CO (k2) have been determined using a flash photolysis–resonance fluorescence technique. Rate constants k1 were determined at room temperature over the pressure range 25–400 torr total pressure of argon, and over the temperature range 298–422 °K at ∼200 torr total pressure of argon. k1 was pressure dependent below ∼200 torr total pressure of argon, but was in the high pressure kinetic region at total pressures ?200 torr. The Arrhenius expression in the high pressure region was k1=1.91×10−12e−(620±400)/RT cm3 molecule−1 sec−1. Rate constants k2 were determined at 299±1 °K with argon and SF6 as diluent gases over the pressure range 25–643 torr total pressure. With argon as the diluent gas k2 showed, within experimental error, little or no pressure dependence as reported earlier from this laboratory. However, with SF6 as the diluent gas k2 increased from (1.53±0.16) ×10−13 cm3 molecule−1 sec−1 at 25 torr total pressure to (3.43±0.35) ...

54 citations


Journal ArticleDOI
TL;DR: In this article, a 1n (10B,α) 7Li nuclear reaction was used to achieve the first visible-wavelength laser having nuclear energy as its only source of excitation.
Abstract: A 6150‐A He‐Hg laser, pumped solely by the 1n (10B,α) 7Li nuclear reaction, has been achieved using the Sandia SPRII reactor The optimum conditions for lasing were 600 Torr total pressure with 25 mTorr Hg partial pressure, with a threshold for lasing of ∼1016 n/cm2 sec This is the first visible‐wavelength laser having nuclear energy as its only source of excitation

34 citations


Journal ArticleDOI
01 Jan 1977
TL;DR: In this article, the propagation of laminar flame fronts through combustible fuel/air mixing layers above a permeable ground plane was investigated using an open trough approximately 240 cm. long, 8 cm. wide, and 25 cm. deep.
Abstract: This investigation concerned the propagation of laminar flame fronts through combustible fuel/air mixing layers above a permeable ground plane. The combustible layers were established by upward diffusion of vapours from a liquid fuel which saturated the permeable ground but did not the ground/air interface. The experiments were carried out using an open trough approximately 240 cm. long, 8 cm. wide, and 25 cm. deep with a smooth ground plane constructed of 100 micrometer glass beads. Ignition, by hot wire, was at one end of the trough, approximately at the stoichiometric mixture level. The fuels were benzene, hexame, heptane, and methyl alcohol. Flame front propagation speeds were determined cinematographically. Total pressure variations prior to, and through the front were measured by a microphone, and the fuel concentration variation above the ground plane were determined by an IR optical scanning system. Propagation velocities of some two to four meters/second were observed, depending upon fuel type and thickness of the combustible zone; no precursor blast waves or detonations were observed. The pressure variations through the propagating flame front were found to have the same magnitude as those of a normal laminar flame. A steady state, quasi-one-dimensional flow theory is presented. Predicted values of propagation velocities were in good agreement with experimental values as a function of fuel type and thickness of the combustible region of the mixing layer.

26 citations


Patent
03 Nov 1977
TL;DR: In this paper, the ion bombardment parameters, in varying a regulation parameter in order to initiate deposition, and in measuring at each instant the total pressure drop within the vacuum chamber with respect to the initial pressure, were controlled by controllably varying the regulation parameter.
Abstract: The method consists in establishing the ion bombardment parameters, in varying a regulation parameter in order to initiate deposition, in measuring at each instant the total pressure drop within the vacuum chamber with respect to the initial pressure and in controlling the total pressure drop by controllably varying the regulation parameter.

23 citations


Patent
07 Nov 1977
TL;DR: An improved variable volume control assembly for conditioned air systems having an improved air flow amplifying measuring means that amplifies the difference between the total pressure and the static pressure and is sensitive at low pressures as mentioned in this paper.
Abstract: An improved variable volume control assembly for conditioned air systems having an improved air flow amplifying measuring means that amplifies the difference between the total pressure and the static pressure and is sensitive at low pressures, an improved air flow collector-straightener, a critical ratio of the area of the inlet to the area of the expansion chamber, and a vortex filter strategically located within the assembly for maximum reduction of turbulence and noise.

14 citations


Patent
07 Nov 1977
TL;DR: In this article, a flow measuring apparatus with increased sensitivity is described for measuring the flow of gas, particularly through a confined passage, where a tube having a constant or tapered orifice section followed by an abrupt expansion of the orifice is described.
Abstract: A flow measuring apparatus having increased sensitivity is disclosed for measuring the flow of gas, particularly through a confined passage. The flow measuring apparatus comprises a tube having a constant or tapered orifice section followed by an abrupt expansion of the orifice; a total pressure sensing probe is located preferably in the section of the tube with the constant or tapered orifice, the total sensing probe having an opening parallel to the flow of gas and facing upstream; and a static pressure sensing probe is located in the walls of the tube in the expanded orifice section immediately after the abrupt expansion, the static pressure probe having an opening either parallel to the flow of gas and facing downstream or perpendicular to the flow of gas. The sensing probes may be connected to a measuring device that provides a readout of the sensed pressures or pressure differential or to a control unit that is responsive to the sensed pressures or pressure differential.

13 citations


Journal ArticleDOI
TL;DR: In this article, the attainable maximum pressure and the small signal gain were compared at pressures up to 3 bar in a TE-CO2 laser amplifier with two preionization systems.
Abstract: The attainable maximum pressure and the small signal gain are compared at pressures up to 3 bar in a TE-CO2 laser amplifier with two preionization systems. It is found that doping with tripropylamine increases the attainable pressure for glow discharges but decreases the small signal gain. At slightly superatmospheric pressure and low doping amount the simple lamberton-Pearson device gives the best results. For constant input energy the inversion grows with increasing total pressure.

12 citations


Patent
11 Aug 1977
TL;DR: In this paper, a system for the detection and location of leaks in pipelines for oil, water and gas, the pressure gradients are measured at the start and end of the section concerned, together with the total pressure differential, and a cross correlation function is produced and the location of the leak is determined from a quoted formula.
Abstract: In a system for the detection and location of leaks in pipelines for oil, water and gas, the pressure gradients are measured at the start and end of the section concerned, together with the total pressure differential After subtraction, a cross correlation function is produced and the location of the leak is determined from a quoted formula This results in a reliable location of a leak even at small leakage rates of 2% and when the fluid flow is not stationary

01 Jan 1977
TL;DR: In this paper, three airblast injectors and an air-assist nozzle were used to improve the spatial fuel-air distribution, and the best results were obtained with an airblast configuration that used multiple cones to provide high velocity air for atomization and also straightened the inlet airflow.
Abstract: Spatial fuel distributions, degree of vaporization, pressure drop and air velocity profiles were measured. Three airblast injectors and an air-assist nozzle were tested. Air swirlers were used to improve the spatial fuel-air distribution. The work was done in a 12 cm tubular duct. Test conditions were: a pressure of 0.3 and 0.5 MPa, inlet air temperatures up to 800 K, air velocities of 10 20 m/s and fuel-air ratios up to 0.020. The fuel was Jet A. The best results were obtained with an airblast configuration that used multiple cones to provide high velocity air for atomization and also straightened the inlet airflow. With this configuration, uniform spatial fuel-air distributions were obtained with mixing lengths greater than 17.8 cm. In this length, vaporization of the fuel was 98.5 percent complete at an inlet air temperature of 700 K. The total pressure loss was 1.0 percent with a reference velocity of 20 m/s and 0.25 percent at 10m/s. The air velocity was uniform across the duct and no autoignition reactions were observed.

Journal ArticleDOI
TL;DR: In this paper, the chemical transport rate of the nonstoichiometric titanium sulfide within the TiS 2 phase region using iodine as transport agent was investigated, with the result that the transport rate depends on the composition of the starting materials.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the kinetics of the gas-phase thermal decomposition of 1,1,2-trifluoro-2, trifluoromethyl-cyclopropane to 2,3,3-tetrafluoropropene and CF2 in the temperature range of 539-604°K and with a total pressure of 17 to 300 torr of a 1:20 mixture of reactant and perfluoroethylene.
Abstract: The kinetics of the gas-phase thermal decomposition of 1,1,2-trifluoro-2-trifluoromethyl-cyclopropane to 2,3,3,3-tetrafluoropropene and CF2 was studied in the temperature range of 539–604°K and with a total pressure of 17 to 300 torr of a 1:20 mixture of reactant and perfluoroethylene. Some runs were also made with the reactant only, with initial pressures of 0.2 to 20 torr. The reaction is first order, homogeneous, and the rate constants fit the following Arrhenius relationship: .

Journal ArticleDOI
TL;DR: In this paper, a cloud chamber capable of resolving the droplets formed on individual ions in the tracks of low-energy electrons has been constructed to further the understanding of the biological effects of radiation.
Abstract: To further the understanding of the biological effects of radiation a knowledge of the spatial distribution of ionizations in small volumes is required. A cloud chamber capable of resolving the droplets formed on individual ions in the tracks of low-energy electrons has been constructed. It is made to high-vacuum specifications and contains a mixture of permanent gases and vapours, unsaturated before expansion, at a total pressure of 10 kPa. Condensation efficiencies close to 100% are obtained without significant background from condensation on uncharged particles and molecular aggregates. This paper describes the chamber, associated equipment and method of operation and discusses the performance of the system.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the photon yields at 3 atm total pressure and reached the following maximum values: α-NPO/Xe: 2%, α-nPO/Ar: 5%, POPOP/XE: 9, POPOP+Ar: 20%

Journal ArticleDOI
TL;DR: The number of transfer units increases with the flow rate and with the total pressure with the increase proportional to 0.2 power of the Weber number in which the gas density is used as mentioned in this paper.
Abstract: The number of overall liquid transfer units as a function of the total pressure, flow rate, and nozzle height has been measured for the removal of butane and F-22 refrigerants from water for a flat spray nozzle in a vacuum spray chamber. The number of transfer units increases with the flow rate and with the total pressure with the increase proportional to 0.2 power of the Weber number in which the gas density is used. NOL also increases linearly with length, but more than two-thirds of the mass transfer always takes place in liquid sheet attached to the nozzle. Because the rate of mass transfer in a spray chamber is much greater than in a packed column, vacuum spray stripping is recommended for the removal of refrigerants from water and brine in the freezing and hydrate processes for desalination and other slightly soluble gases from aqueous solution in other processes.

Journal ArticleDOI
TL;DR: In this article, it was shown that when a gas-operated free-piston pressure gauge is used for measuring pressure relative to atmospheric pressure, the usual relative rotation of the piston and cylinder with added masses can produce a pressure effect up to ten times greater than the accuracy of measurements relative to vacuum.
Abstract: It is shown that when a gas-operated free-piston pressure gauge is used for measuring pressure relative to atmospheric pressure, the usual relative rotation of the piston and cylinder with added masses can produce a pressure effect up to ten times greater than the accuracy of measurements relative to vacuum. The magnitude of this pressure effect depends on the rotational frequency and on whether a bell-jar is in place or not.

01 Jul 1977
TL;DR: The sequence of condensation of minerals from a cooling gas of solar composition has been calculated from thermodynamic data over the pressure range 0001-000001 atm, assuming that complete chemical equilibrium is maintained.
Abstract: The sequence of condensation of minerals from a cooling gas of solar composition has been calculated from thermodynamic data over the pressure range 0001-000001 atm, assuming that complete chemical equilibrium is maintained The results suggest that the Ca-Al-rich inclusions Allende and other carbonaceous chondrites are aggregates of the highest temperature condensates Complete condensation of these elements is followed, 100 deg later, by the onset of the crystallization of nickel-iron, forsterite and enstatite Transport of Ca-Al-rich refractory condensates from one part of the nebula to another before the condensation of these lower-temperature phases may have been responsible for the refractory element fractionations between the different classes of chondrites and possibly for the inferred refractory element enrichment of the Moon The temperature gap between the condensation temperatures of nickel-iron and forsterite increases with increasing total pressure Because pressure and temperature probably increased with decreasing heliocentric distance in the solar nebula, Mercury may have accreted from a condensate assemblage having a higher metal/silicate ratio than Venus or Earth which may, in turn, have formed from less oxidized material than Mars

Journal ArticleDOI
TL;DR: In this paper, total temperatures corresponding to the onset of condensation effects were determined for flow over a 0.137m NACA 0012-64 airfoil mounted in the Langley 1/3m transonic wind tunnel.
Abstract: Total temperatures corresponding to the onset of condensation effects were determined for flow over a 0.137-m NACA 0012-64 airfoil mounted in the Langley 1/3-m transonic wind tunnel. Tests were carried out at a total pressure range from 1.2 to 4.5 atm and at free-stream Mach numbers of 0.75, 0.85, and 0.95. No condensation effects were found to occur until total temperatures were below those associated with free-stream saturation. Significant increases in Reynolds number may apparently be obtained by operation at wind tunnel temperatures below those associated with local saturation over the airfoil but above those where effects first occur. For the 0.85 and 0.95 Mach numbers the increase in Reynolds number was at least 15% over those achieved at local saturation conditions for the same pressure range. Higher pressures may have had some detrimental effect in the 0.95 Mach number test.

ReportDOI
01 Sep 1977
TL;DR: In this paper, an experimental investigation of ducted, two stream, subsonic, reactive, turbulent jet mixing with recirculation was conducted, where a primary jet of air at a mass flow rate of 0075 lb/sec and velocity of 700 ft/sec was surrounded by an outer, low velocity, hydrogen stream Data were obtained with hydrogen-air ratios of 0143 and 0107.
Abstract: : An experimental investigation of ducted, two stream, subsonic, reactive, turbulent jet mixing with recirculation was conducted A primary jet of air at a mass flow rate of 0075 lb/sec and velocity of 700 ft/sec was surrounded by an outer, low velocity, hydrogen stream Data were obtained with hydrogen-air ratios of 0143 and 0107 The duct-to-inner nozzle diameter ratio was ten Radial distributions of hydrogen mass fraction, mean axial velocity, turbulence intensity, and total pressure as well as axial distributions of wall hydrogen mass fraction and wall static pressure are presented for axial stations from one-half to five duct diameters from the nozzle exit plane Comparison of the experimental data with calculations assuming frozen or equilibrium chemistry indicate that he measured velocity, pressure, and composition data are, in general, self-consistent The maximum turbulent intensities which occurred in the center of the mixing layer and within the recirculation eddy were very high having values of 20 percent of the jet exit velocity The velocity and composition field indicate that, while and mixing in the reactive flow field is slower than for the nonreactive case, the reaction had little effect on the size and location of the recirculation zone within the mixing duct

01 May 1977
TL;DR: In this paper, a short annular dump diffuser having a geometry conductive to formation of suction stabilized toroidal vortices in the region of abrupt area change was tested and the overall diffuser area ratio was 4.0 and the length to inlet height ratio was 2.0.
Abstract: A short annular dump diffuser having a geometry conductive to formation of suction stabilized toroidal vortices in the region of abrupt area change was tested. The overall diffuser area ratio was 4.0 and the length to inlet height ratio was 2.0. Performance data were obtained at near ambient temperature and pressure for inlet Mach numbers of 0.18 and 0.30 with suction rates ranging from 0 to 18 percent of total inlet mass flowrate. Results show that the exit velocity profile could be readily biased toward either wall by adjustment of inner and outer wall suction rates. Symmetric exit velocity profiles were inherently unstable with a tendency to revert to a hub or tip bias. Diffuser effectiveness was increased from about 38 percent without suction to over 85 percent at a total suction rate of 10 to 12 percent. At the same time diffuser total pressure loss was reduced from 3.1 percent to 1.1 percent at an inlet Mach number of 0.3.

Journal ArticleDOI
TL;DR: In this paper, a study was initiated on the behavior of the total pressure during the sputtering process for a d.c. triode sputtering system, and the authors found that the increase in the deposition rate of films during reactive sputtering of metals is related to a chemical reaction of the sputtered atoms with the reactive gas.

01 Apr 1977
TL;DR: The viscous flow phenomena associated with sharp and blunt trailing edge airfoils were investigated in this paper, where the upper surface boundary layer was measured in both the attached and separated flow regions.
Abstract: The viscous flow phenomena associated with sharp and blunt trailing edge airfoils were investigated. Experimental measurements were obtained for a 17 percent thick, high performance GAW-1 airfoil. Experimental measurements consist of velocity and static pressure profiles which were obtained by the use of forward and reverse total pressure probes and disc type static pressure probes over the surface and in the wake of sharp and blunt trailing edge airfoils. Measurements of the upper surface boundary layer were obtained in both the attached and separated flow regions. In addition, static pressure data were acquired, and skin friction on the airfoil upper surface was measured with a specially constructed device. Comparison of the viscous flow data with data previously obtained elsewhere indicates reasonable agreement in the attached flow region. In the separated flow region, considerable differences exist between these two sets of measurements.

Journal ArticleDOI
TL;DR: In this paper, a small pitch yaw pressure probe was used for remote traversing in the vertical axis and remote yawing of plus or minus 180 deg. The calibration of the probe indicates a useful pitch angle range of about + or minus 45 deg.
Abstract: Detailed experimental measurements have been made of separated flow fields on a two-dimensional airfoil at low speeds. A rather small pitch yaw pressure probe was chosen. This probe has the capability of remote traversing in the vertical axis and remote yawing of plus or minus 180 deg. The calibration of the probe indicates a useful pitch angle range of about plus or minus 45 deg. The probe and its calibrations provide static and total pressure information as well as three components of velocity. Description and calibration of the probe and typical velocity and pressure plots of the separated flow fields are included.

Journal ArticleDOI
TL;DR: In this article, the authors studied a room-temperature vacuum system with a surface area of 6000 cm2 and a volume of 17 l, pumped by a Ti-ball sublimator and an ion pump.
Abstract: In the proposed Intersecting Storage Accelerator, ISABELLE, 1200 pumping stations will be used to keep two 3‐km‐long rings at a pressure of 1×10−11 Torr (1.3×10−9 Pa). It is clear that in such a large system, price and simplicity are very important. We have therefore undertaken a study on a well‐instrumented room‐temperature vacuum system with a surface area of 6000 cm2 and a volume of 17 l, pumped by a Ti‐ball sublimator and an ion pump. Total pressure and residual gas composition were measured by a Helmer gauge and a quadrupole mass spectrometer. The final pressures of ∠1×10−11 Torr (∠1.3×10−9Pa) were reached with Ti films and a 20‐l s−1 sputter‐ion pump. The main residual gas components were hydrogen and methane. The ultimate pressure was determined primarily by the ability of Ti films to pump H2 and depends on the method of laying down the film and the surface temperature. Previous surface preparation seemed relatively unimportant. Two methods of pumping CH4 were investigated, namely, (a) cracking the...

Proceedings ArticleDOI
01 Jan 1977
TL;DR: In this paper, the effect of diffuser wall acoustic treatment on inlet total pressure loss was investigated in a wind tunnel at forward velocities to 41 meters per second for inlet throat Mach numbers of.5 to.8 and angles of attack as high as 50 degrees.
Abstract: Experimental determination of the effect of diffuser wall acoustic treatment on inlet total pressure loss. Data were obtained by testing an inlet model with 10 different acoustically treated diffusers differing only in the design of the Helmholtz resonator acoustic treatment. Tests were conducted in a wind tunnel at forward velocities to 41 meters per second for inlet throat Mach numbers of .5 to .8 and angles of attack as high as 50 degrees. Results indicate a pressure loss penalty due to acoustic treatment that increases linearly with the porosity of the acoustic facing sheet. For a surface porosity of 14% the total pressure loss was 21% greater than that for an untreated inlet. The penalty resulting from treatment increased for average throat Mach numbers above approximately .7 where local regions of sonic or supersonic surface flow were encountered. Pressure loss over the treatment was not affected by the presence of noise.

Proceedings ArticleDOI
27 Mar 1977
TL;DR: In this article, a three-shock-type cascade was found to be an optimum design and wind tunnel measurements resulted in static pressure ratios of the order of 6 and total pressure ratio of 0.77 at inlet Mach numbers of 2.2.
Abstract: The outlet conditions of supersonic compressor rotors designed for very high total pressure ratios can be highly supersonic (impulse rotors). Then the following stator blade row has to build up high static pressure ratios at supersonic inlet conditions. This paper describes part of a research work which should answer, if it is at all possible to realize such high static pressure ratios in a cascade. Cascades with convergent-divergent blade passages were designed and optimized by boundary layer calculations. In a first step no flow turning was incorporated in the blade sections. A three-shock-type cascade was found to be an optimum design The wind tunnel measurements resulted in static pressure ratios of the order of 6 and total pressure ratios of 0.77 at inlet Mach numbers of 2.2. In a second step the flow turning to axial direction was realized. For that two types of cascades were built and tested. One was a tandem type cascade and the other a single row cascade. The experiments at inlet design conditions resulted in static pressure ratios of the order of 6.5 and total pressure ratios of 0.72.Copyright © 1977 by ASME

Book ChapterDOI
01 Jan 1977
TL;DR: In this paper, the pitot and static tubes for measurement of incompressible flow have been discussed, and the characteristics of the Pitot tube and static tube for measuring total pressure are discussed.
Abstract: This chapter discusses the characteristics of the pitot and static tubes for measurement of incompressible flow. In incompressible flow, the velocity pressure can be obtained from the difference between two pressure observations: the total pressure and the static pressure. The measurement of total pressure is relatively simple. On the surface of any solid body immersed in a stream of fluid, there is some point at which the fluid is brought to rest and the pressure acting is the total pressure of the undisturbed flow. This pressure can be determined by providing an orifice at that point and connecting it to a manometer. This is the basis of the pitot tube, which has been universally adopted for the measurement of total pressure. Pitot-static tubes are the only practical standards of reference for the measurement of air speed against which all other designs, and indeed all anemometers, have to be calibrated either directly or indirectly.

Journal ArticleDOI
TL;DR: In this article, the mass-spectronetric, the thermo-balance and the torsion-effusion techniques in the temperature range: 980-1135 K were used to determine the pressure of the vapor over Ga2 Te2.